An easement in gross involves only one property. In an easement in gross, there is no dominant tenement. This is very common for utility companies. They need to cross people's property, but they are not going to another property.
It is a right which attaches to an individual person or legal entity. So, for example, if you have an easement in gross to cross your neighbor's land onto your land, it means that the easement is for your own personal use and may not be a right which would be included with your land, should you choose to sell your land. An easement in gross does not transfer with the property when it is sold.